Matrix is a harmless memory resident polymorphic virus. It works only under Windows 95 and 98. It stays resident in the Windows memory as a device driver (VxD) by switching from application mode to Windows kernel mode (Ring3->Ring0). It hooks disk files access functions and infects PE executable files with EXE and SCR extensions. The virus affects DOS's COM files, also.
Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.
A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:
Check for the latest database updates
First check if your F-Secure security program is using the latest updates, then try scanning the file again.
Submit a sample
After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.
Note: If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.
Exclude a file from further scanning
If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.
Note: You need administrative rights to change the settings.
While infecting a PE EXE file, the virus encrypts itself and writes itself to the end of the file. The virus patches the startup code of the program with a short routine that passes control to the main virus code. While affecting DOS's COM files, the virus writes a short routine to the end of the file which has no infection abilities, but just displays a message on the 7th of July:
vWake up, Neo... The Matrix has you... w9x.mATRiX
The virus also changes the C:\WINDOWS\WIN.COM file in the same way. On the 6th of April, the virus modifies the following Registry key:
HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer NoClose = 1
As a result the user cannot switch off the computer. You can get rid of this key by downloading and runnung the special REG file that is available on our ftp site:
ftp://ftp.europe.F-Secure.com/anti-virus/tools/matrix_d.reg
The virus also deletes several anti-virus database files:
AVP.CRC, ANTI-VIR.DAT, IVB.NTZ, CHKLIST.MS.
The virus contains some text strings:
where 'xxxxxxx' is the "generation" number of the virus.
Please use the DOS version of FSAV and the latest updates to safely remove this virus. Use the above mentioned REG file to remove the trojanized Registry entry.